The invention relates to a machine for continuously. packing, in particular, food or pharmaceutical products in plastic material containers which are sealed after filling.
Machines of this type are already known, in which the containers are produced by thermoforming a plastic material film, receive one or more doses of products, are sealed by welding or bonding to their upper face a film of material such as aluminium, a metal coated paper, or a plastic material, then go to a cutting station to be separated from each other or in groups of four, six, eight or twelve for example.
The essential drawback of these known machines is their lack of adaptability to a change of format of the containers. It should be understood that, when the plastic material film in which the containers are thermoformed, is moved from one end to the other of the machine, the tools and/or accessories of the different thermoforming, dosage, sealing and cutting stations must be controlled in perfect synchronism with respect to the movements of the plastic material film and must be positioned exactly with respect to the containers formed from the film. For this reason, the known machines are generally equipped with a longitudinal transmission shaft, the different stations are positioned very precisely and mounted permanently on the frame of the machine, and the synchronization of the tools with the travelling speed of the plastic material film is provided initially in the factory, at the time of construction of the machine. The result is that, when it is necessary to modify the machine because for example of a change of format of the containers or groups of containers, it is not sufficient to change some tools or accessories such as the thermoforming molds, the number and position of the product dosing nozzles, the number and position of the means for welding the covers and the cutting blades, it is further necessary to reposition the different stations and resynchronize the whole of the machine, which corresponds in fact to substantially complete reconstruction of the machine. That can only be done in the factory, by specialized staff, and these modification operations are extremely time-consuming and expensive.
The object of the invention is essentially to provide a machine of the above type but which is "flexible" and adaptable simply and rapidly, on the spot, to modifications such as change of format of the containers or groups of containers etc . . .
The invention also provides a machine of the above type which is more reliable and more accurate than those of the prior art.